Cellular telecommunications networks typically comprise a plurality of base stations which each serve a plurality of User Equipment (UE). The plurality of base stations each have a coverage area (usually called a “cell”), within which a UE may connect to and receive telephony and data services from the base station. Cellular networking protocols also have defined processes for allowing a UE to disconnect from one base station and connect to another base station with minimal disruption to ongoing services. This is typically known as a handover.
There are several identifiers associated with UEs, such as the International Mobile Equipment Identifier (IMEI) and the International Mobile Subscriber Identifier (IMSI). The IMEI is a unique number used to identify the UE device and is typically stored within a non-removable memory module of the UE. The IMSI is a unique number used to identify the subscriber (i.e. the user), and is typically stored on a memory module of an integrated circuit card (such as a Subscriber Identity Module (SIM) card). In practice, a user subscribes to telephony and/or data services from a Mobile Network Operator (MNO) and this subscription is associated with an IMSI and a SIM card. The user may then receive these subscribed-for services through a UE by associating it with the IMSI (usually by connecting the SIM card to a SIM-card interface on the UE).
The concept of a multi-subscriber-UE has been introduced to provide improved services for consumers with high cellular networking demands. A multi-subscriber-UE is a single device that may be associated with a plurality of different subscriptions for cellular networking services. The multi-subscriber-UE may set up a connection to a base station for each subscription, and thereafter utilize all resources of these subscriptions through a single device. In other words, the multi-subscriber-UE may establish a first bearer for a first subscription, and a second bearer for a second subscription, and combine the resources of both the first and second bearers. Any application running on the multi-subscriber-UE may then use these combined resources via both the first and second bearers as if they are a single resource, such that the maximum data rate for that application is the sum of the data rate of the first bearer and the data rate of the second bearer. In this manner, the multi-subscriber-UE may realize much greater data rates than it would have access to if it were only associated with a single subscription.
The high-data rates of multi-subscriber-UEs can cause problems in the cellular telecommunications network. As several of the subscription-independent-bearers of the multi-subscriber-UE may be served by a single base station, and the data transmissions via these bearers occur contemporaneously as a combined resource, then the instantaneous demand on the serving base station can be significant. It is therefore more likely for a base station to become overloaded when serving such multi-subscriber-UEs when compared to serving a plurality of single-subscription UEs (which are less likely to utilize their resources at the same time).
It is therefore desirable to alleviate some or all of the above problems.